Through a partnership between investigators in the Cancer Research Network (CRN) and Dana-Farber/Harvard Cancer Center, we propose to develop a resource with sufficient depth and breadth to support high quality cancer comparative effectiveness research (CER) addressing two key knowledge gaps. First, we will focus on treatment of advanced disease. Advanced cancer results in the bulk of deaths, morbidity, and expenditures. Moreover, the evidence base for treatment of advanced disease is often thin and based on expert consensus achieved through extrapolation from small efficacy studies in highly selected cohorts. The second key gap we will address is the relative dearth of population-based research on patterns and outcomes of cancer care for patients who aren't represented in SEER-Medicare, the dominant data source in the field, namely, patients younger than 65, those receiving their care in an HMO, and the poor. We will capitalize on pre-existing infrastructure with focused activities aimed at selective enhancement of resources to support CER studies in patients with advanced cancer. Specifically, we will: Aim 1. Build broad capacity by assembling national data sets (CRN, SEER-Medicare, Medicaid, and NCCN) to support studies of patterns of care and outcomes among patients with advanced cancer and developing, validating, and implementing strategies to enhance the accuracy of key data elements; Aim 2. In one region (California) augment the patient level data from the national sources in Aim 1 with regional data on supply to build a comprehensive cancer "map" of the region; Aim 3. Test capacity and understand limitations of the data systems assembled in Specific Aims 1 and 2 by conducting 5 "use case" analyses that describe patterns of care for select decisions in advanced cancer that span the major treatment modalities, have significant clinical or economic ramifications, and are likely influenced by patient, provider, and/or health system factors;and Aim 4. Launch CE analyses that capitalize on the resources developed and tested in Aims 1-3 by (a) conducting analyses to fully determine the CE of two interventions for advanced cancer, (b) designing and vetting a CE trial appropriate for the CRN, and (c) partnering with NCI to convene a national stakeholders meeting where project data will be presented and strategies for future CER research in cancer discussed. This project will create a sustainable resource for cancer CER, generate new and improved methods to help advance the field of cancer CER, and provide insights into the nature and causes of variation in important patterns of cancer care. It will also lay the groundwork for future cancer CER research by exploring the feasibility of CE trials in the CRN and engaging national stakeholders in a discussion of future research directions. PUBLIC HEALTH RELEVANCE: Advanced cancer is an ideal topic for comparative effectiveness research because the existing evidence base is less well-developed than for early disease, and the potential impact of CER therefore greater. The primary beneficiaries of this work will be cancer patients, since a better understanding of the most effective strategies of care could lead to meaningful improvements in the length and quality of their lives. But policy-makers and taxpayers could benefit as well, if this research reveals that patients at the end of life are receiving care that is not only ineffective, but also costly.